LG Residential Battery

7 questions to ask before buying an energy storage system ?

30 August 2019

Home energy storage systems make the most of solar power and cheaper electricity by storing it so you can use the energy when you need it. They are particularly useful for people with home renewable energy systems who can use more of the green energy they generate at home.

An energy storage system can reduce your fuel bills and carbon emissions, especially if you already have home solar panels. A Residential Energy Storage Systems offer considerable energy and cost saving benefits such as:

  • Solar Battery Storage - storing excess generation from the homeowner’s solar power system

  • Peak Shifting -  Use Economy 7/10 to buy cheap electricity at night and store it for use in the day 

  • Grid Services - interacting with the grid to provide grid balancing services and wholesale electricity trading

  • Battery Storage Back-up - providing a back-up in the event of a power cut.

But choosing the right a battery storage system is not straightforward.  Below we have listed some of the questions you need to ask before deciding which energy storage system is right for you.

What battery storage capacity do I need to run my home ? 

This will depend on a number of factors including whether or not you have solar panels, and the generation capacity of those solar panels. If you are generating 4kW but the battery can only store 2kW and you’re using 1kW in your home then 1kW will still be exported to the grid, losing free energy. It also depends on whether you are trying to go off grid and if you also want back-up in the event of a power cut.  Last but not least the choice also depends on how much you want to invest in an energy storage battery and how quickly you want it to pay for itself.

The home battery’s charging and discharge rate should meet your energy demands?

Some battery storage systems can only deliver 1kW of power. This does not work if you want a cup of coffee and your kettle needs 2kW.  Your home battery storage system needs to be sized to be able to cope with peak demands.  So it’s essential that you understand the power output needed before you buy, otherwise you may find yourself taking energy from the grid even though you have energy stored in your battery.

What should my energy storage battery’s chemistry be and why is this important? 

There are two main types of battery storage system available to buy:

  • Lead Acid, or

  • Lithium Ion

Lead Acid is an older type of battery technology so is cheap to buy and install, but it’s inefficient in energy output, heavy and also is not warranted for long periods of time as the Lead batteries themselves degrade relatively quickly. The price of Lithium batteries is higher, but  they are much better value. They last far longer and will deliver more kWhs (units) during their lifetime.

How to choose the right inverter - The inverter choice is as important as the battery itself as it manages the energy ?

An energy storage battery works with an inverter in a similar way to solar panels. A solar battery can use the inverter that was installed with your solar panels as long as it is a hybrid inverter. Although this can limit the use of the battery to only being used as a battery for solar storage as it can impact grant payments if not installed appropriately. The alternative solution is to use an additional AC coupled inverter which has a number of benefits including increased power output and flexibility in the location of the inverter and battery storage system. Whichever inverter you choose it needs to be high quality as poor quality inverters can result in energy loss.

Do you want your solar battery storage system installed indoors e.g. in a garage or utility room or do you need it installed outside ?

If indoor space is an issue then you may want to install a solar battery storage system outside. If so this will have an impact on the options you have as not all battery storage systems and battery inverters are capable of being located outside. You need to ensure the system you choose is IP rated and warranted for outside use. 

How often do you plan on charging and discharging your Energy Storage System (ESS) ?

Most Home Storage Batteries are warranted or guaranteed for a number of “cycles”. A cycle refers to one complete discharge and one complete charge of the solar battery. So you need to know how many cycles a home storage battery is warranted for. The true length of the warranty in years will depend on how many times the battery is partially charged rather than fully charged as a partial charge or discharge does not count as a full cycle. Most batteries keep track of their charge and discharge % for warranty purposes.

Do you want back-up power from your Energy Storage Battery for use during power cuts ?

Most Energy Storage Systems are designed just for storage of solar energy, solar batteries or to support peak shifting (buying cheap using at peak tariff times) as well. These battery storage solutions do not have a back-up for use during power cuts. However, some renewable energy storage systems can offer a backup capability. These systems can provide power when there’s a power-cut. There are a couple of additional things to consider though when deciding to opt for a solution that has back-up capability.

  • You’ll need a larger storage capacity to keep some power in reserve. If backup is essential, we can design bespoke solutions for you to choose from.

  • Also to prevent damage to your battery or appliances some of your circuits may need to be rewired, this will need checking prior to installation. 

At Romatech we specialise in helping our customers to find the right energy storage systems to meet their needs. Visit our Energy Storage web-page or give us a call on 01223 736900 to find out more.

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